Application of a discontinuous reception (DRX) cycle

ABSTRACT

The present disclosure concerns radio communication. More particularly, the present disclosure inter alia introduces the possibility for a user equipment (UE) to apply a temporary DRX cycle during the time period when the UE transitions from an IDLE mode to a CONNECTED mode. Thus, the disclosure presents an example method performed by a UE. The UE is configured to be either in an IDLE mode or in a CONNECTED mode. The method implemented in the UE comprises applying the temporary DRX cycle during the time period when the UE is in transition from the IDLE mode to the CONNECTED mode.

This application is a 371 of International Application No.PCT/SE2014/050397, filed Apr. 3, 2014, which claims the benefit of U.S.Provisional Application No. 61/811,961, filed Apr. 15, 2013, thedisclosure of which is fully incorporated herein by reference.

TECHNICAL FIELD

Embodiments of the present technology presented herein generally relateto radio communication. More particularly, the embodiments presentedherein generally relate to the application, or utilization, of adiscontinuous reception (DRX) cycle.

BACKGROUND

This section is intended to provide a background to the variousembodiments of the technology that are described in this disclosure. Thedescription herein may include concepts that could be pursued, but arenot necessarily ones that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, what is described in thissection is not prior art to the description and/or claims of thisdisclosure and is not admitted to be prior art by the mere inclusion inthis section.

Radio communication networks are widely deployed to provide variouscommunication services such as telephony, video, data, messaging,broadcasts, and so on. Such communication networks supportcommunications for multiple user equipments (UEs) by sharing theavailable network resources. One example of such a network is theUniversal Mobile Telecommunications System (UMTS), a third generation(3G) mobile phone technology standardized by the 3rd GenerationPartnership Project (3GPP). UMTS includes a definition for a RadioAccess Network (RAN), referred to as UMTS Terrestrial Radio AccessNetwork (UTRAN). The UMTS, which is the successor to Global System forMobile Communications (GSM) technologies, supports various air interfacestandards, such as Wideband-Code Division Multiple Access (W-CDMA), TimeDivision-Code Division Multiple Access (TD-CDMA), and TimeDivision-Synchronous Code Division Multiple Access (TD-SCDMA). The UMTSalso supports enhanced 3G data communications protocols, such as HighSpeed Packet Access (HSPA), which provides higher data transfer speedsand capacity to associated UMTS networks. As the demand for mobilebroadband access continues to increase, research and developmentcontinue to advance the UMTS technologies not only to meet the growingdemand for mobile broadband access, but to advance and enhance the userexperience with mobile communications. For example, third-generationUMTS based on W-CDMA has been deployed in many places the world. Toensure that this system remains competitive in the future, 3GPP began aproject to define the long-term evolution of UMTS cellular technology.The specifications related to this effort are formally known as EvolvedUMTS Terrestrial Radio Access (E-UTRA) and Evolved UMTS TerrestrialRadio Access Network (E-UTRAN), but are more commonly referred to by thename Long Term Evolution (LTE). More detailed descriptions of radiocommunication networks and systems can be found in literature, such asin Technical Specifications published by, e.g., the 3GPP. The corenetwork (CN) of the evolved network architecture is sometimes referredto as Evolved Packet Core (EPC) and when referring to a completecellular system, including both radio access network and core network,as well as other possible entities, such as service related entities,the term Evolved Packet System (EPS) can be used.

As a mere background only, FIG. 1A illustrates an example 3GPP LTE radiocommunication system 100. Accordingly, FIG. 1A illustrates a radioaccess network in an LTE radio communication system 100. In thisexample, there are two radio network nodes 110 a and 110 b, each ofwhich is exemplified as an evolved NodeB, eNB. A first eNB 110 a isconfigured to serve one or several UEs, 120 a-e, located within theeNB's 100 a geographical area of service or the radio cell 130 a. TheeNB 110 a is connectable to a CN. The eNB 110 a is also connectable,e.g. via an X2 interface, to a neighboring eNB 110 b configured to serveanother cell 130 b. Accordingly, the second eNB 110 b is configured toserve one or several UEs, 120 f-j, located within the eNB's 100 bgeographical area of service or the cell 130 b. The eNB 110 b is alsoconnectable to a CN.

A currently popular vision of the future development of thecommunication in radio communication networks comprises huge numbers ofsmall autonomous devices, which typically, more or less infrequently(e.g. once per week to once per minute) transmit and receive only smallamounts of data (or are polled for data). These devices are not assumedto be associated with humans, but are rather sensors or actuators ofdifferent kinds, which communicate with application servers (whichconfigure the devices and receive data from them) within or outside thecellular network. Hence, this type of communication is often referred toas machine-to-machine (M2M) communication and the devices may be denotedmachine devices (MDs). In the 3GPP standardization, the correspondingalternative terms are machine type communication (MTC) and machine typecommunication devices (MTC devices), with the latter being a subset ofthe more general term UE. More detailed descriptions of MTCcommunication can be found in literature, e.g., in the TechnicalSpecification 3GPP TS 22.368 V.12.0.0.

With the nature of MTC devices and their assumed typical uses followthat these devices will often have to be energy efficient, sinceexternal power supplies will often not be available and since it isneither practically nor economically feasible to frequently replace orrecharge their batteries. In some scenarios, the MTC devices may noteven be battery powered, but may instead rely on energy harvesting, e.g.gathering energy from the environment, that is, utilizing (the oftenlimited) energy that may be tapped from sun light, temperaturegradients, vibrations, etc. For such energy deprived devices, whosetraffic is characterized by relatively small and more or less infrequenttransactions (often delay tolerant), it may be important to minimizetheir energy consumption, e.g. between and in conjunction with thecommunication events. These devices generally consume energy between thevarious communication events, e.g. by keeping the radio receiver activeto monitor transmissions from the cellular network. Since the periodsbetween the communication events are generally much longer than theactual communication events, this energy consumption may represent asignificant part of the overall energy consumption and may even dominatethe energy consumption in scenarios where the communication events areinfrequent or very infrequent.

The inventors have realized that the actual uplink (UL) transmissionsnaturally consume significant amounts of energy during the communicationevents. This may be magnified by the relatively large control signalingoverhead that may be associated with a certain communication event,especially since an infrequently communicating MTC device (or other UE)will generally go through the idle to connected mode transition prior toevery communication event. FIG. 1B shows a signaling diagramillustrating an example message sequence during the idle to connectedmode transition in LTE. As can be seen, the signaling procedure involvedduring idle to connected mode transition for a UE may be relativelyextensive.

A mechanism that has been introduced in radio communication networks inorder to save energy in the UEs, e.g. between communication events, isdiscontinuous reception (DRX), which allows a UE to remain in anenergy-saving sleep state most of the time, while waking up to listenfor pages in idle mode DRX or downlink resource assignments (i.e.downlink transmissions) in connected mode DRX. Furthermore, in order tomake the DRX mechanism even more effective for energy MTC devices, 3GPPis currently working on extending the maximum DRX cycle length, and thusthe sleep period, both for idle mode DRX cycle and the connected modeDRX cycle. A DRX cycle thus essentially consists of a sleep periodfollowed by an active period and this cycle is repeated over and overagain until the device is detached from the network. Typically, but notnecessarily, the sleep period is longer than the active period. A DRXcycle may have a more complex structure than described above, e.g.including a few repetitions of a shorter DRX cycle at the end of theactive period, but for the purpose of this disclosure, the simplifiedDRX cycle description suffices in order to understand the principles ofthe various embodiments described herein. The idle mode DRX cycle, i.e.,the paging cycle, is generally configured in the UE through parametersin the system information (SI) that is broadcast in each radio cell, inconjunction with UE specific parameters in the form of IMSI modulo1024,and an optional UE specific DRX cycle length. Alternatively, it is alsopossible to configure a UE specific paging cycle. The connected mode DRXcycle and other DRX parameters (when used) may be configured in the UEthrough optional parameters typically in theRRCConnectionReconfiguration message, or later in connected mode. A moredetailed description of DRX mechanisms can be found in literature, suchas in the reference book 4G LTE/LTE-Advanced for Mobile Broadband byErik Dahlman, Stefan Parkvall and Johan Sköld, Academic Press, 2011,ISBN:978-0-12-385489-6, see e.g. chapter 13.2.6 “Discontinuous Reception(DRX) and Component Carrier Deactivation”. More detailed descriptions ofDRX cycles can also be found in, e.g. 3GPP TS 36.304 V.11.3.0 (see e.g.chapter 7), 3GPP TS 36.300 V.11.5.0 (see e.g. chapter 12), 3GPP TS36.321 V.11.2.0 (see e.g. chapter 5.7). As will be appreciated, the DRXmechanisms are defined for both idle mode and connected mode. Generallyspeaking, these DRX mechanisms are excellent UE energy savingmechanisms.

However, the inventors have realized that when the communication eventsare short and infrequent, each communication event is likely to bepreceded by an idle to connected mode transition, and this transition islikely to take a significant portion of time from the whole time neededto perform the data transmission. The potential use of long connectedmode DRX cycles may increase the risk of radio link failure duringmobility between radio cells, which means that idle to connected modetransition may be triggered many times in such scenarios too. Inaddition, since the connection setup procedure often involves exchangeof a large number of signaling messages, this control planecommunication is likely to dominate i.e. comprise more messages, largerdata volumes and consume more energy, over the user plane communication.Furthermore, since the signaling procedure involves many nodes in thenetwork as well as significant processing in the network nodes, e.g. inorder to set the appropriate configuration parameters, the timeintervals separating the messages may be significant. Hence, having theMTC device (or other UE) actively listening for downlink transmissionsduring the entire idle to connected mode transition, due to the lack ofDRX sleep mode possibilities, may cause an a relatively high UE energyconsumption in many scenarios. In turn, this may have a significantnegative impact on the battery lifetime of a UE, e.g. a MTC device.

SUMMARY

It is in view of the above considerations and others that the variousembodiments disclosed herein have been made.

In one of its aspects, the technology presented herein concerns a methodperformed by a user equipment (UE). The UE is configured to be either inan idle mode (i.e. an idle state) or in a connected mode (i.e. aconnected state). The method comprises applying a discontinuousreception (DRX) cycle during a time period when the UE is in transitionfrom the idle mode to the connected mode. It is to be understood thatalthough the DRX cycle may be applied during the entire time periodduring which the UE is in transition from the idle mode to the connectedmode, the DRX cycle does not necessarily have to be applied during theentire transition from the idle mode to the connected mode. In otherwords, the DRX cycle is not necessarily applied during the entire timeperiod during which the UE is in transition from the idle mode to theconnected mode. Instead, the DRX cycle may be applied during a part, orportion, of the transition from the idle mode to the connected mode.That is, the DRX cycle may be applied during a part, or portion, of thetime period during which the UE is in transition from the idle mode tothe connected mode. The idle mode and the connected mode, respectively,may be RRC states. RRC is an abbreviation for Radio Resource Control asis known among persons skilled in the art. That is to say that the idlemode may be an RRC_IDLE mode. Also, the connected mode may be aRRC_CONNECTED mode.

This method differs from the existing prior art in that it allows forapplying, or utilizing, a DRX mechanism during the time period when theUE is in transition from the idle mode (e.g. RRC_IDLE) to the connectedmode (e.g. RRC_CONNECTED). In the existing art, neither the idle modeDRX cycle nor the connected mode DRX cycles are applied during the timeperiod when the UE is in transition from the idle mode to the connectedmode. Accordingly, in the existing art no DRX cycle is applied duringthe time period when the UE is in transition from the idle mode to theconnected mode.

Advantageously, the above-mentioned DRX cycle may be a temporary DRXcycle. For example, the temporary DRX cycle may be applied only when theUE is in transition from the idle mode to the connected mode. When theUE has transitioned to the connected mode (e.g. RRC_CONNECTED), thetemporary DRX cycle may be inactivated, or even invalidated. The DRXcycle may therefore be called temporary DRX cycle, since it is onlyutilized when the UE is in the transition from the idle mode to theconnected mode. In some embodiments, the method may thus compriseceasing to apply the temporary DRX cycle when the UE has transitioned tothe connected mode (e.g. RRC_CONNECTED). Or said differently, the methodmay comprise stopping to apply the temporary DRX cycle upon the UEentering the connected mode.

The method may also comprise applying one or several DRX configurationparameters during the time period when the UE is in transition from theidle mode to the connected mode. Again, although the one or several DRXconfiguration parameters may be applied during the entire time periodduring which the UE is in transition from the idle mode to the connectedmode, the one or several DRX configuration parameters are notnecessarily applied during the entire time period during which the UE isin transition from the idle mode to the connected mode. Instead, the oneor several DRX configuration parameters may be applied during a part, orportion, of the time period during which the UE is in transition fromthe idle mode to the connected mode.

In one embodiment, the method may comprise, prior to applying the DRXcycle during the time period when the UE is in transition from the idlemode to the connected mode, transmitting a data message to a radionetwork node, wherein the data message comprises a request to apply theDRX cycle during the time period when the UE is in transition from theidle mode to the connected mode. The method may also comprise, prior toapplying the DRX cycle during the time period when the UE is intransition from the idle mode to the connected mode, receiving a datamessage from the radio network node, wherein the data message comprisesan acknowledgement of said request.

In some embodiments, the method may comprise, prior to applying the DRXcycle during the time period when the UE is in transition from the idlemode to the connected mode, retrieving the DRX cycle to be appliedduring the time period when the UE is in transition from the idle modeto the connected mode. For example, retrieving the DRX cycle to beapplied during the time period when the UE is in transition from theidle mode to the connected mode may comprise receiving a data messagefrom a radio network node, the data message comprising information aboutthe DRX cycle. Additionally, or alternatively, retrieving the DRX cycleto be applied during the time period when the UE is in transition fromthe idle mode to the connected mode may comprise retrieving informationabout the DRX cycle from a memory associated with the UE.

In some embodiments, the method may comprise, prior to applying the DRXcycle during the time period when the UE is in transition from the idlemode to the connected mode, retrieving DRX configuration parameter(s) tobe applied during the time period when the UE is in transition from theidle mode to the connected mode. For instance, retrieving the DRXconfiguration parameter(s) to be applied during the time period when theUE is in transition from the idle mode to the connected mode maycomprise receiving a data message from a radio network node, wherein thedata message comprises the DRX configuration parameter(s). Additionally,or alternatively, retrieving the DRX configuration parameter(s) to beapplied during the time period when the UE is in transition from theidle mode to the connected mode may comprise retrieving the DRXconfiguration parameter(s) from a memory associated with the UE.

In another of its aspects, the technology presented herein concerns amethod performed by a radio network node. The method comprisestransmitting a data message to a user equipment (UE), wherein the datamessage comprises information about a DRX cycle to be applied by the UEduring the time period when the UE is in transition from the idle modeto the connected mode. The method may additionally comprise transmittinga data message to the UE, wherein the data message comprises DRXconfiguration parameter(s) to be applied by the UE during the timeperiod when the UE is in transition from the idle mode to the connectedmode.

In yet another of its aspects, the technology presented herein concernsa method performed by a radio network node. The method comprisesreceiving a data message from a user equipment (UE), wherein the datamessage comprises a request to apply a DRX cycle during the time periodwhen the UE is in transition from the idle mode to the connected mode.The method may additionally comprise transmitting a data message to theUE, wherein the data message comprises an acknowledgement of saidrequest.

In still another of its aspects, the technology presented hereinconcerns a user equipment (UE) configured to be either in an idle modeor in a connected mode. The UE comprises a processor, and a memorystoring computer program code, which, when run in the processor causesthe UE to apply a discontinuous reception (DRX) cycle during a timeperiod when the UE is in transition from the idle mode to the connectedmode. As mentioned earlier, although the DRX cycle may be applied duringthe entire time period during which the UE is in transition from theidle mode to the connected mode, the DRX cycle does not necessarily haveto be applied during the entire transition from the idle mode to theconnected mode. In other words, the DRX cycle is not necessarily appliedduring the entire time period during which the UE is in transition fromthe idle mode to the connected mode. Instead, the DRX cycle may beapplied during a part, or portion, of the transition from the idle modeto the connected mode. That is, the DRX cycle may be applied during apart, or portion, of the time period during which the UE is intransition from the idle mode to the connected mode.

Also as mentioned earlier, the DRX cycle may be a temporary DRX cycle.For example, the memory may store computer program code, which, when runin the processor causes the UE to apply the temporary DRX cycle onlywhen the UE is in transition from the idle mode to the connected mode.

In some embodiments, the memory may store computer program code, which,when run in the processor causes the UE to cease to apply the temporaryDRX cycle when the UE has transitioned to the connected mode.

In some embodiments, the memory may store computer program code, which,when run in the processor causes the UE to apply one or several DRXconfiguration parameters during the time period when the UE is intransition from the idle mode to the connected mode.

For example, the UE may also comprise a transmitter configured totransmit a data message to a radio network node, wherein the datamessage comprises a request to apply the DRX cycle during the timeperiod when the UE is in transition from the idle mode to the connectedmode. Moreover, the UE may comprise a receiver configured to receive adata message from the radio network node, the data message comprising anacknowledgement of said request.

In some embodiments, the memory may also store computer program code,which, when run in the processor causes the UE to retrieve the DRX cycleto be applied during the time period when the UE is in transition fromthe idle mode to the connected mode. Also, the receiver may beconfigured to receive a data message from a radio network node, whereinthe data message comprises information about the DRX cycle.Additionally, or alternatively, the memory may store computer programcode, which, when run in the processor causes the UE to retrieveinformation about the DRX cycle from a memory associated with the UE.

Furthermore, the memory may store computer program code, which, when runin the processor causes the UE to retrieve the DRX configurationparameters to be applied during the time period when the UE is intransition from the idle mode to the connected mode. Also, the receivermay be configured to receive a data message from a radio network node,wherein the data message comprises the DRX configuration parameters.Additionally, or alternatively, the memory may store computer programcode, which, when run in the processor causes the UE to retrieve the DRXconfiguration parameters from a memory associated with the UE.

The above-mentioned UE may be a Machine Type Communication (MTC) device.

In another of its aspects, the technology discussed herein concerns aradio network node. The radio network node comprises a transmitterconfigured to transmit a data message to a user equipment (UE), whereinthe data message comprises information about a DRX cycle to be appliedby the UE during the time period when the UE is in transition from theidle mode to the connected mode. The transmitter may also be configuredto transmit a data message to the UE, wherein the data message comprisesDRX configuration parameters to be applied by the UE during the timeperiod when the UE is in transition from the idle mode to the connectedmode.

The radio network node may be an evolved NodeB (eNB). Alternatively, theradio network node may be a Home Subscriber Server (HSS). Alternatively,the radio network node may be a Mobility Management Entity (MME). Yetfurther, it is conceivable that a distributed solution is utilized. Thatis, several of the eNB, HSS and MME may implement the herein describedfunctionality of the radio network node in a distributed manner. It isalso conceivable that embodiments described herein can be applied in aUMTS system, e.g. providing a W-CDMA or HSPA radio interface, in whichcase the radio network node may be a Node B, a Radio Network Controller(RNC), a HSS, a Home Location Register (HLR) or a Serving General PacketRadio Service Support Node (SGSN) or a distributed solution involvingseveral of these nodes.

In still another of its aspects, the technology discussed hereinconcerns a radio network node. The radio network node comprises areceiver configured to receive a data message from a user equipment(UE), wherein the data message comprises a request to apply a DRX cycleduring the time period when the UE is in transition from the idle modeto the connected mode. The radio network node may further comprise atransmitter configured to transmit a data message to the UE, wherein thedata message comprises an acknowledgement of said request.

The radio network node may be an evolved NodeB (eNB). Alternatively, theradio network node may be a Home Subscriber Server (HSS). Alternatively,the radio network node may be a Mobility Management Entity (MME). Yetfurther, it is conceivable that a distributed solution is utilized. Thatis, several of the eNB, HSS and MME implement the herein describedfunctionality of the radio network node in a distributed manner. It isalso conceivable that embodiments described herein can be applied in aUMTS system, e.g. providing a W-CDMA or HSPA radio interface, in whichcase the radio network node may be a Node B, a Radio Network Controller(RNC), a HSS, a Home Location Register (HLR) or a Serving General PacketRadio Service Support Node (SGSN) or a distributed solution involvingseveral of these nodes.

As will be appreciated and according to some of the embodimentsdescribed throughout this disclosure, it is proposed to apply a DRXcycle during a time period when the UE is in transition from the idlemode to the connected mode. Advantageously, the DRX cycle is temporaryand applied only when the UE is in the transition from the idle mode tothe connected mode. As soon as the UE is in connected mode, the normal(or, regular) connected mode DRX cycle can be applied in a conventionalway.

Applying a DRX cycle in the time period between idle mode and connectedmode provides several advantages. For example, this may allow the UE tosave power during its transition from idle mode to connected mode.Indeed, much energy is generally consumed during the multitude oftransitions between idle mode and connected mode. This may beparticularly true for MTC devices, since the idle-to-connected modetransition signaling procedure may represent a significant part of thetotal communication for these devices. Therefore, allowing MTC devicesto save power during the otherwise power-consuming idle-to-connectedmode transition signaling procedure may be beneficial. It should beappreciated that the above advantage is not limited to MTC devices. Alsoother UEs, such as many of today's smartphones, would benefit fromreducing power consumption during the idle-to-connected mode transitionsignaling procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages will be apparent andelucidated from the following description of various embodiments,reference being made to the accompanying drawings, in which:

FIG. 1A shows an example 3GPP LTE radio communication system;

FIG. 1B shows a signaling diagram during a time period when a UEtransitions from an idle mode to a connected mode;

FIG. 2 shows a flowchart of a method according to an embodimentperformed in a user equipment;

FIG. 3 shows a flowchart of a method according to an embodimentperformed in a user equipment;

FIG. 4 shows a flowchart of a method according to an embodimentperformed in a user equipment;

FIG. 5 shows a flowchart of a method according to an embodimentperformed in a radio network node;

FIG. 6 shows a flowchart of a method according to an embodimentperformed in a radio network node;

FIG. 7 shows an example embodiment of a user equipment; and

FIG. 8 shows an example embodiment of a radio network node.

DETAILED DESCRIPTION

The technology will now be described more fully hereinafter withreference to the accompanying drawings, in which certain embodiments areshown. The technology may, however, be embodied in many different formsand should not be construed as limited to the embodiments set forthherein; rather, these embodiments are provided by way of example so thatthis disclosure will be thorough and complete, and will fully convey thescope of the technology to those persons skilled in the art. Likereference numbers refer to like elements or method steps throughout thedescription.

As used in this disclosure, the term “user equipment (UE)” is used tomean any device, which can be used by a user to communicate. Also, theterm UE may be referred to as a mobile terminal, a terminal, a userterminal (UT), a wireless terminal, a wireless communication device, awireless transmit/receive unit (WTRU), a mobile phone, a cell phone,etc. Yet further, the term UE includes MTC devices, which do notnecessarily involve human interaction. Also, the term “radio networknode” as used herein generally denotes a fixed point being capable ofcommunicating with the UE. As such, it may be referred to as a basestation, a radio base station, a NodeB or an evolved NodeB (eNB), aRadio Network Controller (RNC), access point, etcetera. Within thecontext of this disclosure it should be understood that the term “radionetwork node” may denote a node that is not necessarily part of what istypically referred to as a “radio access network”, e.g. a MobilityManagement Entity (MME), a Serving General Packet Radio Service SupportNode (SGSN), a Home Subscriber Server (HSS) or a Home Location Register(HLR). Thus, when used herein the term “radio network node” may alsoinclude, e.g., CN nodes.

In one of its aspects, the technology presented herein concerns theapplication, or utilization, of a discontinuous reception (DRX)mechanism during a time period when a user equipment (UE) is intransition from an idle mode to a connected mode. It should beappreciated that although the DRX cycle may be applied during the entiretime period during which the UE is in transition from the idle mode tothe connected mode, the DRX mechanism does not necessarily have to beapplied during the entire transition from the idle mode to the connectedmode. In other words, the DRX mechanism is not necessarily appliedduring the entire time period during which the UE is in transition fromthe idle mode to the connected mode. Instead, the DRX mechanism may beapplied during a part, or portion, of the transition from the idle modeto the connected mode. That is, the DRX mechanism may be applied duringa part, or portion, of the time period during which the UE is intransition from the idle mode to the connected mode.

FIG. 2 shows a flowchart of a method implemented in a UE according to anexample embodiment. That is, a method 200 performed by a UE is proposed.The UE is configured to be either in an idle mode (e.g. RRC_IDLE) or ina connected mode (e.g. RRC_CONNECTED). The method comprises applying 210a DRX cycle during a time period when the UE is in transition from theidle mode to the connected mode. The DRX cycle may be a temporary DRXcycle. Furthermore, the temporary DRX cycle may be applied only when theUE is in transition from the idle mode to the connected mode. In otherwords, the temporary DRX cycle is not applied when the UE is in idlemode (e.g. RRC_IDLE). Similarly, the temporary DRX cycle is not appliedwhen the UE is in connected mode (e.g. RRC_CONNECTED). Rather, thetemporary DRX cycle is only applied when the UE is in a transitionbetween the two modes, i.e. when the UE is in a transition from the idlemode to the connected mode. For example, the time period when the UE isin transition from the idle mode to the connected mode may be understoodto mean the time period from step 1 (i.e. RA Msg 1, where RA is anabbreviation for Random Access) up to and including step 21 (i.e.RRCConnectionReconfigurationComplete) in FIG. 1B.

The method may preferably also comprise applying 220 one or several DRXconfiguration parameters during the time period when the UE is intransition from the idle mode to the connected mode. DRX configurationparameters may, for example, include one or more of the followingparameters:

-   -   DRX start offset (which is generally used to define when the DRX        cycle starts)    -   DRX cycle length    -   On Duration    -   On duration timer    -   DRX Inactivity Timer    -   DRX Retransmission Timer    -   Short DRX cycle    -   Short DRX cycle timer    -   The nB parameter (which is involved in the definition of idle        mode DRX and is described in chapter 7 of 3GPP Technical        Specification 36.304 V11.3.0 “3^(rd) Generation Partnership        Project; Technical Specification Group Radio Access Network;        Evolved Universal Terrestrial Radio Access (E-UTRA); User        Equipment (UE) procedures in idle mode (Release 11)”)

The method may additionally comprise ceasing 230, or stopping, to applythe temporary DRX cycle when the UE has transitioned to the connectedmode. That is, as soon as the UE enters connected mode (e.g.RRC_CONNECTED), the UE may stop applying the temporary DRX cycle. Uponentering the connected mode, the UE may begin applying the normal, orregular, connected mode DRX cycle.

Also, the method may additionally comprise ceasing 240, or stopping, toapply the DRX configuration parameters when the UE has transitioned tothe connected mode. That is, as soon as the UE enters connected mode(e.g. RRC_CONNECTED), the UE may stop applying the DRX configurationparameters. Upon entering the connected mode, the UE may instead beginapplying the normal, or regular, connected mode DRX configurationparameter(s).

Applying a DRX cycle (and optionally also the DRX configurationparameters) in the time period between idle mode and connected mode mayallow the UE to save power during its transition from idle mode toconnected mode. Indeed, much energy is generally consumed during themultitude of transitions between idle mode and connected mode.Therefore, it may be beneficial for many UEs devices to apply atemporary DRX cycle in the idle-to-connected mode transition signalingprocedure, since this signaling procedure may represent a significantpart of the total communication for these devices. Therefore, allowingUEs to save power during the otherwise power-consuming idle-to-connectedmode transition signaling procedure may be advantageous for manydevices.

FIG. 3 shows a flowchart of a method 300 implemented in a UE accordingto another example embodiment. In this embodiment, the UE transmits 310a data message to a radio network node, wherein the data messagecomprises a request to the radio network node to apply the DRX cycleduring the time period when the UE is in transition from the idle modeto the connected mode. In other words, the UE can transmit an indicationto a radio network node that it requests, or wishes, to apply theearlier-mentioned DRX cycle during its transition from idle mode toconnected mode. In one example implementation, the above-mentioned datamessage comprises one or more data fields wherein at least one of thedata fields comprises or otherwise indicates said request to apply theDRX cycle during the time period when the UE is in transition from theidle mode to the connected mode.

In response and if the radio network node accepts the request, the UEmay receive 320 a data message from the radio network node, wherein thereceived data message comprises an acknowledgement (ACK) of saidrequest. In one example implementation, the received data messageincludes one or more data fields where at least one of the data fieldsincludes or otherwise indicates the ACK. Alternatively, if the radionetwork node does not accept the request, the UE may receive 330 a datamessage from the radio network node, wherein the received data messagecomprises a negative acknowledgement (NACK). In one exampleimplementation, the received data message includes one or more datafields where at least one of the data fields includes or otherwiseindicates the NACK. If, or when, the UE receives 320 the ACK from theradio network node, the method continues to the method 200 describedhereinabove. In other words, the transmission 310 of the data messageincluding the above-mentioned request as well as the reception 320 maybe performed prior to the UE applying 210 (see FIG. 2) theidle-to-connected mode transition DRX cycle, i.e. the temporary DRXcycle.

FIG. 4 shows a flowchart of a method 400 implemented in a UE accordingto still another example embodiment. In this embodiment, the UEretrieves 410 the DRX cycle to be applied during the time period whenthe UE is in transition from the idle mode to the connected mode. Forexample, the retrieval 410 of the DRX cycle may comprise receiving 411(see FIG. 4B) a data message from a radio network node, wherein thisdata message comprises information about the DRX cycle. For example, thedata message may comprise one or more data fields wherein at least oneof the data fields comprises or otherwise indicates the informationabout the DRX cycle. Alternatively, the retrieval 410 of the DRX cyclemay comprise retrieving 412 (see FIG. 4C) information about the DRXcycle from a memory associated with the UE, e.g. a memory internal tothe UE. Also, the method may optionally comprise retrieving 420 DRXconfiguration parameters to be applied during the time period when theUE is in transition from the idle mode to the connected mode. Forexample, the retrieval 420 of the DRX configuration parameters maycomprise receiving 421 (see FIG. 4D) a data message from a radio networknode, wherein this data message comprises the DRX configurationparameters. For example, the data message may comprise one or more datafields wherein at least one of the data fields comprises or otherwiseindicates said DRX configuration parameters. Alternatively, theretrieval 420 of the DRX configuration parameters may compriseretrieving 422 (see FIG. 4E) the DRX configuration parameters from amemory associated with the UE, e.g. a memory internal to the UE. As isillustrated in FIG. 4A, the method 400 may precede the method 200 ormethod 300 described with reference to FIGS. 2 and 3, respectively.

It should be appreciated that retrieving 410 the DRX cycle to be appliedduring the time period when the UE is in transition from the idle modeto the connected mode may occur simultaneously, or substantiallysimultaneously, as retrieving 420 DRX configuration parameters to beapplied during the time period when the UE is in transition from theidle mode to the connected mode. In other words, even if FIG. 4Aindicates that these method steps, or actions, occur serially in twosubsequent method steps or actions, it should be appreciated that thesemethods steps, or actions (i.e. 410 and 420), may occur simultaneously,or substantially simultaneously. Thus, in some embodiments these methodssteps, or actions (i.e. 410 and 420), may be seen as occurring in onesingle method step, or action. Alternatively, these method steps, oractions (i.e. 410, 420) may occur in parallel.

Similarly, the method steps, or actions, of receiving 411 (see FIG. 4B)the data message from the radio network node, wherein this data messagecomprises information about the DRX cycle and receiving 421 (see FIG.4D) a data message from a radio network node, wherein this data messagecomprises the DRX configuration parameters do not have to occurserially. Rather, these method steps, or actions, may occursimultaneously, or substantially simultaneously. For example, the datamessages comprising information about the DRX cycle and the DRXconfiguration parameters, respectively, may be a single data messagecomprising both information about the DRX cycle and the DRXconfiguration parameters. Thus, these methods steps, or actions (i.e.411 and 421) may be seen as occurring in one single method step, oraction. Alternatively, these method steps, or actions (i.e. 411, 421)may occur in parallel.

Also in a similar manner, the method steps, or actions, of retrieving412 (see FIG. 4C) information about the DRX cycle from a memoryassociated with the UE (e.g. a memory internal to the UE) and retrieving422 (see FIG. 4E) the DRX configuration parameters from a memoryassociated with the UE (e.g. a memory internal to the UE) may occurserially, in parallel or simultaneously.

The methods 200, 300, and 400 described hereinabove may preferably,though not necessarily, be implemented in, or otherwise performed by, aMTC device.

FIG. 5 shows a flowchart of a method 500 implemented in a radio networknode according to an example embodiment. The radio network nodetransmits 510 a first data message to a user equipment (UE), wherein thefirst data message comprises information about a DRX cycle to be appliedby the UE during the time period when the UE is in transition from theidle mode (e.g. RRC_IDLE) to the connected mode (e.g. RRC_CONNECTED). Inone example implementation, the first data message may comprise one ormore data fields wherein at least one of said data fields comprises orotherwise indicates the information about the DRX cycle to be applied bythe UE during the time period when the UE is in transition from the idlemode to the connected mode. The method may preferably also includetransmitting 520 a second data message to the UE, wherein the seconddata message comprises DRX configuration parameters to be applied by theUE during the time period when the UE is in transition from the idlemode to the connected mode. In one example implementation, the seconddata message may comprise one or more data fields wherein at least oneof said data fields comprises or otherwise indicates said DRXconfiguration parameters to be applied by the UE during the time periodwhen the UE is in transition from the idle mode to the connected mode.

For illustration purpose only, FIG. 5 illustrates the first and seconddata messages as two separate messages. However, the first and seconddata messages do not necessarily have to be transmitted in separate datamessages. Instead, the first and second data messages may be sent in onesingle data message. In fact, those skilled in the art will appreciatethat it may be preferred to transmit the first and second messages inone single data message.

Furthermore, it should also be appreciated that the method shown in FIG.5 may be conditionally performed depending on whether the radio networknode has received a data message from the UE requesting the radionetwork node to return the DRX cycle and/or the DRX configurationparameter(s).

FIG. 6 shows a flowchart of a method 600 implemented in a radio networknode according to another example embodiment. The method 600 comprisesreceiving 610 a data message from a user equipment (UE), wherein thedata message comprises a request to apply a DRX cycle during the timeperiod when the UE is in transition from the idle mode to the connectedmode. Said data message may comprise one or more data fields where atleast one of the data fields comprises or otherwise indicates therequest to apply a DRX cycle during the time period when the UE is intransition from the idle mode to the connected mode

If the radio network node accepts the received 610 request, the methodmay additionally comprise transmitting 620 a data message to the UE,wherein the data message comprises an acknowledgement (ACK) of saidrequest. In one example implementation, the data message may include oneor more data fields where at least one of the data fields includes orotherwise indicates the ACK. Alternatively, i.e. if the radio networknode does not accept the received 610 request, the method may comprisetransmitting 630 a data message to the UE, wherein the data messagecomprises a negative acknowledgement (NACK) of said request, thus,rejecting the received 610 request. In one example implementation, thedata message may include one or more data fields where at least one ofthe data fields includes or otherwise indicates the NACK.

The radio network node may be an evolved NodeB (eNB). Alternatively, theradio network node may be a Home Subscriber Server (HSS). Alternatively,the radio network node may be a Mobility Management Entity (MME). Yetfurther, it is conceivable that a distributed solution can be utilized.That is, several of the eNB, HSS and MME implement the herein describedfunctionality of the radio network node in a distributed manner. It isalso possible that the embodiments described herein can be applied in aUMTS system, e.g. providing a W-CDMA or HSPA radio interface, in whichcase the radio network node may be a Node B, a Radio Network Controller(RNC), a HSS, a Home Location Register (HLR) or a Serving General PacketRadio Service Support Node (SGSN) or a distributed solution involvingseveral of these nodes.

It should be appreciated that the methods 500 and 600 can be combined.

Some exemplary embodiments of the technology will now be described insome more detail hereinafter:

As is understood from the above, it is proposed to introduce apossibility to apply a DRX mechanism (i.e. DRX cycle and/or DRXconfiguration parameter(s)) during the idle to connected mode transitionsignaling procedure. The DRX cycle and/or the DRX configurationparameter(s) may be temporary. Thus, the DRX cycle and/or the DRXconfiguration parameter(s) may advantageously be used only during theidle to connected mode transition procedure. When the idle to connectedmode transition signaling procedure is finalized, the temporary DRXconfiguration may be invalidated. Then, the connected mode DRXconfiguration which is generally conveyed in theRRCConnectionReconfiguration RRC message at the end of the idle toconnected mode transition signaling procedure (see FIG. 1B) may takeover. Alternatively, if no connected mode DRX is configured in theRRCConnectionReconfiguration RRC message, the UE may continue to operatewithout DRX mechanism in connected mode. As yet another alternative, ifno connected mode DRX is configured in the RRCConnectionReconfigurationRRC message, the UE may continue to operate with the temporary DRXconfiguration (which is thus thereafter to be regarded as regular,non-temporary DRX configuration).

Various detailed embodiments will be described in the following. Inorder to support the application, or utilization, of a DRX mechanismduring the idle to connected mode transition signaling procedure, novelDRX configuration possibilities are proposed herein below. This may beachieved in a number of different ways, which are elaborated in thesubsections below. Following these subsections is also a subsectionabout avoidance of potential incompatibility challenges.

The signaling to use a temporary DRX mechanism during the idle toconnected mode transition signaling procedure may comprise thefollowing: 1) Indication of temporary DRX configuration usage, 2)Deriving the temporary DRX configuration.

In the first step, the UE may indicate to the network (or, rather, oneor more radio network nodes of said network) that it will use or wouldprefer to use a temporary DRX configuration. In the latter case, thenetwork may need to confirm the usage of the configuration. There aremultiple options where the indication from the UE to the network may beincluded:

-   -   Indication in the RRCConnectionRequest message (see FIG. 1B);    -   Indication in the RRCConnectionSetupComplete message (see FIG.        1B);    -   Indication in the subscriber data;    -   Indication in a Non-Access Stratum (NAS) message (see e.g. 3GPP        TS 24.301 V.11.4.0)    -   Indication in RA Msg1 (see FIG. 1B)    -   Based on device category or capability;

In the second step, the UE may derive the temporary configuration to beused during the RRC Connection Setup procedure (i.e. the idle toconnected mode transition procedure) until the actual, semi-permanentconfiguration is received in the RRCConnectionReconfiguration message.The parameter types (e.g. various timers) used to define the temporaryDRX configuration should preferably be the same as the ones used fordefinition of regular connected mode DRX configurations. There aremultiple options for this:

-   -   The network may signal the temporary DRX configuration to the UE        in the system information (SI);    -   The temporary DRX configuration may be signaled in the        RRCConnectionSetup message;    -   The temporary DRX configuration may be preconfigured in        subscriber data;    -   The temporary DRX configuration may be signaled in a NAS message        (see e.g. 3GPP TS 24.301 V.11.4.0);    -   The temporary DRX configuration may be signaled in RA Msg2 (see        e.g. FIG. 1)    -   The temporary DRX configuration may be hard-coded in accordance        with future 3GPP technical specifications.

The above two steps (indication and derivation) may not necessarilyoccur in this order. The UE may retrieve the temporary DRX configurationbefore it indicates to the network that it will use or would prefer touse the temporary DRX configuration. The two steps may also beintegrated with each other, so that the indication comprises theconfiguration parameters, in which case the two steps occursimultaneously, or essentially simultaneously.

1.1. Indication in the RRCConnectionRequest Message

In one embodiment, the UE is configured to indicate in theRRCConnectionRequest RRC message (see e.g. 3GPP TS 36.331 V.11.1.0) thatit wishes to apply a temporary DRX configuration during the idle toconnected mode signaling procedure. The indication, or request, couldcome in various shapes. In its simplest form the indication, or request,may be a flag, e.g. one bit, indicating that temporary DRX should beapplied. The actual configuration parameters to be applied could then beeither standardized or signaled in the system information (SI)message(s). A slightly more elaborated alternative would be to let theindication, or request, have the form of an index indicating one out ofa set of possible temporary DRX configurations. The DRX configurationparameters that each index value maps to could be standardized orsignaled in a SI message(s). Still another alternative would be that theUE includes the complete set of DRX configuration parameters in theRRCConnectionRequest message. A combination, where a subset of thetemporary DRX configuration parameters are indicated in theRRCConnectionRequest message while the rest are standardized or signaledin the SI message(s) is also conceivable. Yet another possibility is toutilize one or both of the spare values of the establishmentCause IE(information element) to indicate that a preconfigured, temporary DRXconfiguration should be applied. Using both spare values provides thepossibility to indicate two different temporary DRX configurations. TheestablishmentCause IE is further detailed in 3GPP TS 36.331. It wouldeven be possible to change the interpretation of the value of theestablishmentCause IE that currently indicates ‘delay tolerant access’so that it also indicates that a preconfigured temporary DRXconfiguration is applied by the UE. The preconfigured parameters couldbe standardized or indicated in signaled system information. Onepossibility is to restrict the use of temporary DRX configuration to thedelay tolerant establishment cause. One of the spare bits of theRRCConnectionRequest message can be used in combination with thisestablishment cause. An indication in the RRCConnectionRequest messagecombined with temporary DRX parameters in the system information isprobably, but not necessarily, the most attractive of the alternativespresented herein. It allows the temporary DRX configuration to beapplied immediately after the RRCConnectionRequest message and may allowan operator flexibility to define the actual parameters to be used forthe temporary DRX configuration.

1.2. Indication in the RRCConnectionRequest and Configuration in theRRCConnectionSetup Messages

In one embodiment, the UE and the eNB may “cooperate” to configure thetemporary DRX cycle. The UE may, for example, indicate in theRRCConnectionRequest message, in either of the ways described above insection 1.1, that it wishes, or requests, to apply temporary DRX duringthe idle to connected mode transition signaling procedure. The eNB maythen respond with the actual temporary DRX configuration parameters inthe RRCConnectionSetupRRC message, thereby concluding the configuration.

1.3. Indication in the RRCConnectionSetupComplete Message

In one embodiment, the UE may indicate in the RRCConnectionSetupCompletemessage that it wishes, or requests, to apply a temporary DRXconfiguration during the idle to connected mode signaling procedure.This is similar to the alternative with indication in theRRCConnectionRequest message (see section 1.1). A difference is that theestablishmentCause IE is not included in the RRCConnectionSetupCompletemessage, so the spare values of that IE are not used, or cannot be used.

A difference of this approach compared to the example of including theindication in the RRCConnectionRequest message is that the temporary DRXconfiguration cannot be applied until the RRCConnectionSetupCompletemessage has been sent, which means that the UE cannot save energy in DRXsleep mode while waiting for the RRCConnectionSetup RRC message (i.e. RAMsg4, see FIG. 1) from the eNB.

On the other hand, an advantage of this approach compared to the exampleof including the indication in the RRCConnectionRequest message is thatthere is generally more room for extensions in theRRCConnectionSetupComplete message than in the RRCConnectionRequestmessage (for which the ambition in 3GPP has been to keep it very short).As a result, according to the current RRC specification (see 3GPP TS36.331 V.11.1.0), the RRCConnectionSetupComplete message can be extendedwith a non-critical extension, whereas the RRCConnectionRequest messagecannot generally be extended in this manner. This makes it easier toinclude more elaborate information, such as a complete set ofconfiguration parameters for the temporary DRX configuration in theRRCConnectionSetupComplete message.

1.4. Preconfigured in Subscriber Data

In one embodiment, the temporary DRX configuration is included in thesubscriber data associated with the UE. Hence, it may be stored in theHSS (Home Subscriber Server) and in the USIM (Universal SubscriberIdentity Module) in the UE. As described for the alternative ofincluding an indication and potentially configuration in theRRCConnectionRequest message (see section 1.1), the indication (or,request) and configuration can come in various forms. The sameindication alternatives as described in section 1.1 can be used incombination with this embodiment. The indication and/or configurationmay be downloaded from the HSS to the MME (Mobility Management Entity)together with other subscriber data when the UE registers in the MME.From the MME the indication/temporary configuration may be forwarded tothe eNB in the first message from the MME to the eNB in the idle toconnected mode transition procedure, e.g. the Initial Context SetupRequest S1AP message (message 17 in the message sequence of FIG. 1B) orthe Downlink NAS Transport S1AP message carrying the AuthenticationRequest NAS message (message 9 in the message sequence of FIG. 1B) (seee.g. also 3GPP TS 36.413 V11.1.0).

According to this embodiment, the UE can apply the temporary DRXconfiguration after sending the RRCConnectionSetupComplete message,since the eNB will receive the temporary DRX configuration indication(or full parameter set) from the MME before it sends its next message tothe UE. Optionally, the eNB (and the UE) activates the temporary DRXconfiguration only if the eNB has previously received an indication ineither the RRCConnectionRequest message (a new indication, e.g. one ofthe currently unused values of the establishmentCause IE, or tied to anexisting value of the establishmentCause IE) or theRRCConnectionSetupComplete message. If this option is used, it shouldpreferably be extended such that the indication from the UE triggers theeNB to include a similar indication in the Initial UE Message S1APmessage (i.e. message 6 in the message sequence of FIG. 1B) to triggerthe MME to forward the temporary DRX configuration information to theeNB (and in the absence of such an indication from the eNB the MME wouldnot forward the temporary DRX configuration information). Afterreceiving the indication in the RRCConnectionRequest message or based onsome other reason, the eNB may optionally confirm usage of temporary DRXconfiguration in the RRCConnectionSetup message with a one bit flag.

1.5. Explicit Indication in a NAS Message

According to one embodiment, the UE indicates in a NAS (Non-AccessStratum) message to the MME that it wishes (or requests) to apply atemporary DRX configuration during the idle to connected mode transitionsignaling procedure. The NAS message (see e.g. 3GPP TS 24.301 V11.4.0)should preferably, but not necessarily, be the one that is included inthe RRCConnectionSetupComplete RRC message (i.e. message 5 in themessage sequence of FIG. 1B). In FIG. 1B this NAS message is a ServiceRequest NAS message, but in other scenarios it may also be another NASmessage, such as an Attach Request NAS message, an Extended ServiceRequest NAS message or a Tracking Area Update Request NAS message.

In order to inform the eNB, the MME can forward the indication (or,request) to the eNB in the Initial Context Setup Request S1AP message(i.e. message 17 in the message sequence of FIG. 1B) or the Downlink NASTransport S1AP message carrying the Authentication Request NAS message(i.e. message 9 in the message sequence of FIG. 1B).

It will be appreciated that the same examples for the indication, orrequest, as described in section 1.1 may be used in combination withthis embodiment.

According to this embodiment, the UE can apply the temporary DRXconfiguration after sending the indication in the NAS message, i.e.after sending the RRCConnectionSetupComplete message, since (similar tothe case where the temporary DRX indication is included in thesubscriber data) the eNB will receive the temporary DRX configurationindication (or full parameter set) from the MME before it sends its nextmessage to the UE.

1.6. Based on Device Category or Capability

According to another embodiment, the indication is associated with acategory or capability of the UE. It could then be included in any ofthe IEs in the Attach Request NAS message that indicates variousproperties of the UE, i.e. the UE network capability IE, the MS networkcapability IE, the Mobile station classmark 2 IE or the Deviceproperties IE. As these IEs are included in a NAS message they aredelivered to the MME. Hence, the MME can inform the eNB so that it mayapply the temporary DRX configuration. The MME can do this by forwardingthe indication to the eNB in the Initial Context Setup Request S1APmessage (i.e. message 17 in the message sequence of FIG. 1B) or theDownlink NAS Transport S1AP message carrying the Authentication RequestNAS message (i.e. message 9 in the message sequence of FIG. 1B). Again,the same examples for the indication as described in section 1.1 may beused also with this embodiment, i.e. in combination with thisembodiment.

After receiving the temporary DRX indication (irrespective of its levelof elaboration) the MME would keep it in the UE context (i.e. itsrecords of UE associated information) and in case of an MME relocation,the indication would be forwarded to the new MME.

Another, more preferable variant of basing the solution on the UEcapability is to make use of radio capability related parameters. Inthis variant the UE-EUTRA-Capability IE may be extended with thetemporary DRX indication/configuration. The same elaborationalternatives for the indication as described in section 1.1 may be usedalso with this alternative.

In the current RRC specification (see e.g. 3GPP TS 36.331 V11.1.0), theUE-EUTRA-Capability IE is included in the ue-CapabilityRAT-Container IE,which in turn is included in the ue-CapabilityRAT-ContainerList IE inthe UECapabilityInformation message.

In conjunction with the Attach procedure (i.e. when the UE firstregisters in the network and relevant contexts are established in corenetwork nodes, such as the MME, the SGW and the PGW) the eNB may requestthe capability information from the UE by sending the RRC messageUECapabilityEnquiry to the UE. The UE may then respond with the RRCmessage UECapabilityInformation, including the capability information asdescribed above. The eNB may then forward the information to the MME asfollows. It includes the UECapabilityInformation message in aue-RadioAccessCapabilityInfo IE, which it includes in aUERadioAccessCapabilityInformation message (which is specified as an RRCmessage), which in turn is included in a UE Radio Capability IE, whichthe eNB sends to the MME in the S1AP message UE CAPABILITY INFOINDICATION. The MME may store the UE capability information in its UEcontext and keeps it for as long as the UE remains attached to thenetwork (and transfers it to a new MME in case of MME relocation).

In subsequent cases (during the same attach session) where the UEconnects to the network, i.e. transits from idle to connected mode, theMME transfers the UE capability information to the eNB in the in the UERadio Capability IE in the S1AP message INITIAL UE CONTEXT SETUP REQUEST(message 17 in the message sequence in FIG. 1B). The UE Radio CapabilityIE is optional in the INITIAL UE CONTEXT SETUP REQUEST message andduring the Attach procedure it is absent. This absence triggers the eNBto request the information from the UE and forward it to the MME, asdescribed above.

This mechanism may allow the eNB to apply the temporary DRXconfiguration when it has received the UE capability information fromthe MME, i.e. starting with the transmission of message 18 in FIG. 1B,i.e. the downlink RRC message SecurityModeCommand. From the UE'sperspective this means that it may apply the temporary DRX configurationafter receiving the preceding downlink message in the sequence, i.e.after receiving message 14 in FIG. 1B. Note that messages 7-16 areoptional in the message sequence of FIG. 1B, but the UE cannot know inadvance whether they will be used or not. Therefore the UE cannot applythe temporary DRX configuration after receiving the RRCConnectionSetupmessage (message 4 in FIG. 1B), which means that if messages 7-16 inFIG. 1B are not used, the UE will not apply the temporary DRXconfiguration until it has received the SecurityModeCommand message(message 18 in FIG. 1B) from the eNB.

Similar to the embodiment with the temporary DRX indication in thesubscriber data (see section 1.4) an option is to let the activation ofthe temporary DRX configuration be triggered by an indication from theUE, using the same mechanism as described in section 1.4. This optionmay be used with both the method variants elaborated in this section.

1.7 Indication in a MAC Control Element

In one embodiment, the UE indicates in a MAC (Medium Access Control)Control Element that it wishes, or requests, to apply a temporary DRXconfiguration during the idle to connected mode signaling procedure. TheMAC Control Element would preferably be included in the MAC PDU(Protocol Data Unit) carrying one of the uplink RRC messages, e.g.(preferably) the RRCConnectionRequest RRC message or theRRCConnectionSetupComplete RRC message, but it could also be conveyed ina separate MAC PDU (i.e. a MAC PDU without SDU). Optionally, theindication could be confirmed by the eNB in a MAC Control Element in asubsequent downlink MAC PDU, preferably a MAC PDU carrying one of thedownlink RRC messages, e.g. the RRCConnectionSetup RRC message (assumingthat the indication was conveyed in the MAC PDU carrying theRRCConnectionRequest RRC message). The same alternatives of thetemporary DRX indication as described in section 1.1 may be used incombination with this embodiment, e.g. a flag or an index, full orpartial configuration (or a combination).

1.8. Indication in RA Msg1 and/or RA Msg2

With this embodiment, the indication (or request) of application of atemporary DRX configuration is included in the first and/or the secondmessage of the random access procedure, i.e. RA Msg1 (random accesspreamble) or RA Msg2 (Random Access Response MAC PDU) (messages 1 and 2in the message sequence of FIG. 1B) (see e.g. also 3GPP TS 36.321V11.0.0). If RA Msg1 is used, the only means to indicate anything is touse a preamble from a dedicated group of preambles. This implies thatthe current (maximum) two preamble groups, A and B, would have to becomplemented with another preamble group for indication of temporary DRXconfiguration. A preamble from this group would indicate that temporaryDRX configuration is applied by the UE during the idle to connected modetransition signaling procedure. The actual temporary DRX configurationparameters could be standardized or specified in the system information.If it is desired to be able to indicate one out of a set of temporaryDRX configurations, then a preamble group would have to be defined foreach set. Such preamble groups would be indicated in the systeminformation, just as the presently existing preamble groups A and B.Alternatively, the preamble from a dedicated preamble group may beconsidered as a request for temporary DRX configuration to be used,whereby this must be confirmed by the eNB, (which optionally also mayprovide the actual configuration parameters). The eNB would confirm theusage of the temporary DRX configuration in RA Msg2, which thus mayinclude an indication/configuration of temporary DRX with any of theelaboration alternatives described in section 1.1, i.e. a flag, anindex, full or partial configuration (or a combination). A possiblevariant of using RA Msg2 for this purpose could be that the eNB takesthe initiative to configure the UE with temporary DRX without a priorindication from the UE.

1.9 Avoidance of Incompatibility Problems—Indication of Support ofTemporary DRX in the Cell

For those of the above described embodiments where the UE takes someaction related to the temporary DRX feature before or without receivingany indication of support for the temporary DRX feature in the cell, itmay be beneficial to include a parameter in the system information (SI)indicating support of the temporary DRX feature in the cell. Absence ofthis indication would then imply lack of support, which would make theUE refrain from the temporary DRX feature related action(s) that couldotherwise cause incompatibility problems.

Such actions could be that the UE sends an indication of intentionand/or desire to use the temporary DRX feature or that the UE startsusing the temporary DRX feature. The potential incompatibility problemsthat may be avoided by refraining from such actions could be e.g. thatthe eNB rejects (or discards) a message from the UE including atemporary DRX related indication that the eNB does not understand (orsupport), e.g. the RRCConnectionRequest RRC message or theRRCConnectionSetupComplete RRC message, that the MME rejects a NASmessage including a temporary DRX related indication or that the UEone-sidedly starts using the temporary DRX feature, i.e. goes into DRXsleep mode, causing the UE to miss downlink signaling messages from theeNB.

Turning now to FIG. 7, an example embodiment of a user equipment (UE) 10will be described. The UE 10 may preferably, though not necessarily, beembodied as a MTC device. Furthermore, the UE 10 is configured to beeither in an idle mode (e.g. RRC_IDLE) or in a connected mode (e.g.RRC_CONNECTED). In this embodiment, the UE 10 comprises an interfacemodule 11, a processor 12, and a memory 13. Optionally, the UE 10 mayalso comprise a user interface 14 through which a user can operate andinteract with the UE 10. The interface module 11 may comprise atransmitting module (Tx), or transmitter. The interface module may alsocomprise a receiving module (Rx), or receiver. Alternatively, theinterface module 11 may comprise a transceiving module (Tx/Rx), ortransceiver, with both transmission and reception capabilities.

The memory 13 may store computer program code, which, when run in theprocessor 12 causes the UE 10 to apply a discontinuous reception, DRX,cycle during a time period when the UE is in transition from the idlemode to the connected mode. As mentioned earlier, the DRX cycle may be atemporary DRX cycle. For example, the memory 13 may store computerprogram code, which, when run in the processor 12 causes the UE 10 toapply the temporary DRX cycle only when the UE is in transition from theidle mode to the connected mode.

In some embodiments, the memory 13 may store computer program code,which, when run in the processor 12 causes the UE 10 to cease, or stop,to apply the temporary DRX cycle when the UE has transitioned to theconnected mode (e.g. RRC_CONNECTED).

In some embodiments, the memory 13 may also store computer program code,which, when run in the processor 12 causes the UE 10 to apply one orseveral DRX configuration parameters during the time period when the UEis in transition from the idle mode to the connected mode.

Yet further, the transmitter 11 may be configured to transmit a datamessage to a radio network node, wherein the data message comprises arequest to apply the DRX cycle during the time period when the UE 10 isin transition from the idle mode to the connected mode. Moreover, thereceiver 11 may be configured to receive a data message from the radionetwork node, the data message comprising an acknowledgement of saidrequest.

In some embodiments, the memory 13 may also store computer program code,which, when run in the processor 12 causes the UE 10 to retrieve the DRXcycle to be applied during the time period when the UE 10 is intransition from the idle mode to the connected mode. Also, the receiver11 may be configured to receive a data message from a radio networknode, wherein the data message comprises information about the DRXcycle. Additionally, or alternatively, the memory 13 may store computerprogram code, which, when run in the processor 12 causes the UE 10 toretrieve information about the DRX cycle from a memory associated withthe UE 10. The memory associated with the UE 10 may be the memorydenoted 11. Alternatively, it may be another memory (not shown) of theUE 10. Yet further, it may be another memory (not shown) which isexternal to the UE 10, i.e. not an integral part of the UE 10.

Furthermore, the memory 13 may store computer program code, which, whenrun in the processor 12 causes the UE 10 to retrieve the DRXconfiguration parameters to be applied during the time period when theUE is in transition from the idle mode to the connected mode. Also, thereceiver 11 may be configured to receive a data message from a radionetwork node, wherein the data message comprises the DRX configurationparameters. Additionally, or alternatively, the memory 13 may storecomputer program code, which, when run in the processor 12 causes the UE10 to retrieve the DRX configuration parameters from a memory associatedwith the UE. Again, the memory associated with the UE 10 may be thememory denoted 11. Alternatively, it may be another memory (not shown)of the UE 10. Yet further, it may be another memory (not shown) which isexternal to the UE 10, i.e. the memory is not necessarily an integralpart of the UE 10.

Turning to FIG. 8, an example embodiment of a radio network node 20 willbe described. According to this example embodiment, the radio networknode 20 comprises an interface module 21. The interface module 21 maycomprise a transmitting module (Tx), or transmitter. The interfacemodule 21 may also comprise a receiving module (Rx), or receiver.Alternatively, the interface module 21 may comprise a transceivingmodule (Tx/Rx), or transceiver, with both transmission and receptioncapabilities.

The transmitter 21 may be configured to transmit a data message to auser equipment (UE), wherein the data message comprises informationabout a DRX cycle to be applied by the UE during the time period whenthe UE is in transition from the idle mode to the connected mode. Thetransmitter 21 may also be configured to transmit a data message to theUE, wherein the data message comprises DRX configuration parameters tobe applied by the UE during the time period when the UE is in transitionfrom the idle mode to the connected mode.

The receiver 21 may be configured to receive a data message from a userequipment (UE), wherein the data message comprises a request to apply aDRX cycle during the time period when the UE is in transition from theidle mode to the connected mode. In response, the transmitter 21 may beconfigured to transmit a data message to the UE, wherein the datamessage comprises an acknowledgement (ACK) of said request.Alternatively, the transmitter 21 may be configured to transmit a datamessage to the UE, wherein the data message comprises a negativeacknowledgement (NACK) of said request.

The radio network node may be an evolved NodeB (eNB). Alternatively, theradio network node may be a Home Subscriber Server (HSS). Alternatively,the radio network node may be a Mobility Management Entity (MME). Yetfurther, it is conceivable that a distributed solution is utilized. Thatis, one or several of the eNB, HSS and MME may implement the hereindescribed functionality of the radio network node in a distributedmanner.

According to some of the embodiments described throughout thisdisclosure, it is proposed to apply a DRX cycle during a time periodwhen the UE is in transition from the idle mode to the connected mode.Advantageously, the DRX cycle is temporary and applied only when the UEis in the transition from the idle mode to the connected mode. As soonas the UE is in connected mode, the normal (or, regular) connected modeDRX cycle can be applied in a conventional way. Applying a DRX cyclealso in the time period between idle mode and connected mode may providemany advantages as described hereinabove. For example, this may allowthe UE to save power during its transition from idle mode to connectedmode. Allowing UEs to save power during the otherwise power-consumingidle-to-connected mode transition signaling procedure may be beneficialto many UEs, particularly (though not exclusively) MTC devices.

In the detailed description hereinabove, for purposes of explanation andnot limitation, specific details are set forth in order to provide athorough understanding of various embodiments described in thisdisclosure. In some instances, detailed descriptions of well-knowndevices, components, circuits, and methods have been omitted so as notto obscure the description of the embodiments disclosed herein withunnecessary detail. All statements herein reciting principles, aspects,and embodiments disclosed herein, as well as specific examples thereof,are intended to encompass both structural and functional equivalentsthereof. Additionally, it is intended that such equivalents include bothcurrently known equivalents as well as equivalents developed in thefuture, i.e., any elements developed that perform the same function,regardless of structure. Thus, for example, it will be appreciated thatblock diagrams herein can represent conceptual views of illustrativecircuitry or other functional units embodying the principles of theembodiments. Similarly, it will be appreciated that any flow charts andthe like represent various processes which may be substantiallyrepresented in computer readable medium and so executed by a computer orprocessor, whether or not such computer or processor is explicitlyshown. The functions of the various elements including functionalblocks, may be provided through the use of hardware such as circuithardware and/or hardware capable of executing software in the form ofcoded instructions stored on computer readable medium. Thus, suchfunctions and illustrated functional blocks are to be understood asbeing either hardware-implemented and/or computer-implemented, and thusmachine-implemented. In terms of hardware implementation, the functionalblocks may include or encompass, without limitation, digital signalprocessor (DSP) hardware, reduced instruction set processor, hardware(e.g., digital or analog) circuitry including but not limited toapplication specific integrated circuit(s) [ASIC], and/or fieldprogrammable gate array(s) (FPGA(s)), and (where appropriate) statemachines capable of performing such functions. In terms of computerimplementation, a computer is generally understood to comprise one ormore processors or one or more controllers. When provided by a computeror processor or controller, the functions may be provided by a singlededicated computer or processor or controller, by a single sharedcomputer or processor or controller, or by a plurality of individualcomputers or processors or controllers, some of which may be shared ordistributed. Moreover, use of the term “processor” or “controller” shallalso be construed to refer to other hardware capable of performing suchfunctions and/or executing software, such as the example hardwarerecited above.

Although the various embodiments of this disclosure have been describedabove with reference to specific embodiments, it is not intended to belimited to the specific form set forth herein. For example, while manyof the various embodiments have been described mainly with respect toEPS/LTE, it will come to mind to one skilled in the art having benefitof the teachings presented in the foregoing description and associateddrawings that the general principles and concepts described herein canequally possible be utilized in e.g. UMTS/WCDMA/HSPA.

SELECTED EXAMPLE EMBODIMENTS

The technology disclosed herein thus encompasses without limitation thefollowing example embodiments:

Example Embodiment M1

A method performed by a user equipment, UE, wherein the UE is configuredto be either in an idle mode or in a connected mode, the methodcomprising:

-   -   applying a discontinuous reception, DRX, cycle during a time        period when the UE is in transition from the idle mode to the        connected mode.

Example Embodiment M2

The method according to example embodiment M1, wherein the DRX cycle isa temporary DRX cycle.

Example Embodiment M3

The method according to example embodiment M2, wherein the temporary DRXcycle is applied only when the UE is in transition from the idle mode tothe connected mode.

Example Embodiment M4

The method according any one of the example embodiments M2-M3, furthercomprising:

-   -   ceasing to apply the temporary DRX cycle when the UE has        transitioned to the connected mode.

Example Embodiment M5

The method according to any one of the example embodiments M1-M4,further comprising:

-   -   applying one or several DRX configuration parameters during the        time period when the UE is in transition from the idle mode to        the connected mode.

Example Embodiment M6

The method according to any one of the example embodiments M1-M5,further comprising, prior to applying the DRX cycle during the timeperiod when the UE is in transition from the idle mode to the connectedmode:

-   -   transmitting a data message to a radio network node, the data        message comprising a request to apply the DRX cycle during the        time period when the UE is in transition from the idle mode to        the connected mode.

Example Embodiment M7

The method according to the example embodiment M6, further comprising,prior to applying the DRX cycle during the time period when the UE is intransition from the idle mode to the connected mode:

-   -   receiving a data message from the radio network node, the data        message comprising an acknowledgement of said request.

Example Embodiment M8

The method according to any one of the example embodiments M1-M7,further comprising, prior to applying the DRX cycle during the timeperiod when the UE is in transition from the idle mode to the connectedmode:

-   -   retrieving the DRX cycle to be applied during the time period        when the UE is in transition from the idle mode to the connected        mode.

Example Embodiment M9

The method according to example embodiment M8, wherein retrieving theDRX cycle to be applied during the time period when the UE is intransition from the idle mode to the connected mode comprises:

-   -   receiving a data message from a radio network node, the data        message comprising information about the DRX cycle.

Example Embodiment M10

The method according to example embodiment M8, wherein retrieving theDRX cycle to be applied during the time period when the UE is intransition from the idle mode to the connected mode comprises:

-   -   retrieving information about the DRX cycle from a memory        associated with the UE.

Example Embodiment M11

The method according to any one of the example embodiments M1-M10,further comprising, prior to applying the DRX cycle during the timeperiod when the UE is in transition from the idle mode to the connectedmode:

-   -   retrieving DRX configuration parameters to be applied during the        time period when the UE is in transition from the idle mode to        the connected mode.

Example Embodiment M12

The method according to example embodiment M11, wherein retrieving theDRX configuration parameters to be applied during the time period whenthe UE is in transition from the idle mode to the connected modecomprises:

-   -   receiving a data message from a radio network node, the data        message comprising the DRX configuration parameters.

Example Embodiment M13

The method according to example embodiment M11, wherein retrieving theDRX configuration parameters to be applied during the time period whenthe UE is in transition from the idle mode to the connected modecomprises:

-   -   retrieving the DRX configuration parameters from a memory        associated with the UE.

Example Embodiment M14

The method according to any of the previous example embodiments, whereinthe time period when the UE is in transition from idle mode to connectedmode begins when the UE transmits (i.e. sends) an initial Random Accessmessage (see FIG. 1).

Example Embodiment M15

The method according to any of the previous example embodiments, whereinthe time period when the UE is in transition from idle mode to connectedmode ends when the UE transmits (i.e. sends) aRRCConnectionReconfigurationComplete message (see FIG. 1).

Example Embodiment M16

The method according to any of the previous example embodiments, whereinapplying the DRX cycle is started after a transmission or a reception ofa data message during the time period when the UE is in transition fromidle mode to connected mode (see FIG. 1).

Example Embodiment M17

The method according to example embodiment M16, wherein applying the DRXcycle is started after a transmission of a RRCConnectionRequest message(see FIG. 1).

Example Embodiment M18

A method performed by a radio network node, the method comprising:

-   -   transmitting a data message to a user equipment, UE, the data        message comprising information about a DRX cycle to be applied        by the UE during the time period when the UE is in transition        from the idle mode to the connected mode.

Example Embodiment M19

The method according to example embodiment M18, further comprising:

-   -   transmitting a data message to the UE, the data message        comprising DRX configuration parameters to be applied by the UE        during the time period when the UE is in transition from the        idle mode to the connected mode.

Example Embodiment M20

A method performed by a radio network node, the method comprising:

-   -   receiving a data message from a user equipment, UE, the data        message comprising a request to apply a DRX cycle during the        time period when the UE is in transition from the idle mode to        the connected mode.

Example Embodiment M21

The method according to the example embodiment M20, further comprising:

-   -   transmitting a data message to the UE, the data message        comprising an acknowledgement of said request.

Example Embodiment U1

A user equipment, UE, configured to be either in an idle mode or in aconnected mode, the UE comprising:

-   -   a processor; and    -   a memory storing computer program code, which, when run in the        processor causes the UE to apply a discontinuous reception, DRX,        cycle during a time period when the UE is in transition from the        idle mode to the connected mode.

Example Embodiment U2

The UE according to example embodiment U1, wherein the DRX cycle is atemporary DRX cycle.

Example Embodiment U3

The UE according to example embodiment U2, wherein the memory storescomputer program code, which, when run in the processor causes the UE toapply the temporary DRX cycle only when the UE is in transition from theidle mode to the connected mode.

Example Embodiment U4

The UE according any one of the example embodiments U2-U3, wherein thememory stores computer program code, which, when run in the processorcauses the UE to cease to apply the temporary DRX cycle when the UE hastransitioned to the connected mode.

Example Embodiment U5

The UE according to any one of the example embodiments U1-U4, whereinthe memory stores computer program code, which, when run in theprocessor causes the UE to apply one or several DRX configurationparameters during the time period when the UE is in transition from theidle mode to the connected mode.

Example Embodiment U6

The UE according to any one of the example embodiments U1-U5, furthercomprising a transmitter configured to transmit a data message to aradio network node, the data message comprising a request to apply theDRX cycle during the time period when the UE is in transition from theidle mode to the connected mode.

Example Embodiment U7

The UE according to the example embodiment U6, further comprising areceiver configured to receive a data message from the radio networknode, the data message comprising an acknowledgement of said request.

Example Embodiment U8

The UE according to any one of the example embodiments U1-U7, whereinthe memory stores computer program code, which, when run in theprocessor causes the UE to retrieve the DRX cycle to be applied duringthe time period when the UE is in transition from the idle mode to theconnected mode.

Example Embodiment U9

The UE according to example embodiment U8, wherein the receiver isconfigured to receive a data message from a radio network node, the datamessage comprising information about the DRX cycle.

Example Embodiment U10

The UE according to example embodiment U8, wherein the memory storescomputer program code, which, when run in the processor causes the UE toretrieve information about the DRX cycle from a memory associated withthe UE.

Example Embodiment U11

The UE according to any one of the example embodiments U1-U10, whereinthe memory stores computer program code, which, when run in theprocessor causes the UE to retrieve the DRX configuration parameters tobe applied during the time period when the UE is in transition from theidle mode to the connected mode.

Example Embodiment U12

The UE according to example embodiment U11, wherein the receiver isconfigured to receive a data message from a radio network node, the datamessage comprising the DRX configuration parameters.

Example Embodiment U13

The UE according to example embodiment U11, wherein the memory storescomputer program code, which, when run in the processor causes the UE toretrieve the DRX configuration parameters from a memory associated withthe UE.

Example Embodiment U14

The UE according to any of the example embodiments U1-U13, wherein thetime period when the UE is in transition from idle mode to connectedmode begins when the UE transmits (i.e. sends) an initial Random Accessmessage (see FIG. 1).

Example Embodiment U15

The UE according to any of the example embodiments U1-U14, wherein thetime period when the UE is in transition from idle mode to connectedmode ends when the UE transmits (i.e. sends) aRRCConnectionReconfigurationComplete message (see FIG. 1).

Example Embodiment U16

The UE according to any of the example embodiments U1-U15, whereinapplying the DRX cycle is started after a transmission or a reception ofa data message during the time period when the UE is in transition fromidle mode to connected mode (see FIG. 1).

Example Embodiment U17

The UE according to example embodiment U16, wherein applying the DRXcycle is started after a transmission of a RRCConnectionRequest message(see FIG. 1).

Example Embodiment N1

A radio network node, comprising:

-   -   a transmitter configured to transmit a data message to a user        equipment, UE, the data message comprising information about a        DRX cycle to be applied by the UE during the time period when        the UE is in transition from the idle mode to the connected        mode.

Example Embodiment N2

The radio network node according to example embodiment N1, wherein thetransmitter is configured to transmit a data message to a userequipment, UE, the data message comprising DRX configuration parametersto be applied by the UE during the time period when the UE is intransition from the idle mode to the connected mode.

Example Embodiment N3

The radio network node according to example embodiment N1 or N2, whereinthe radio network node comprises one or several of the following: anevolved NodeB (eNB), a Home Subscriber Server (HSS), a MobilityManagement Entity (MME).

Example Embodiment N4

A radio network node, comprising:

-   -   a receiver configured to receive a data message from a user        equipment, UE, the data message comprising a request to apply a        DRX cycle during the time period when the UE is in transition        from the idle mode to the connected mode.

Example Embodiment N5

The radio network node according to the example embodiment N4, furthercomprising a transmitter configured to transmit a data message to theUE, the data message comprising an acknowledgement of said request

Example Embodiment N6

The radio network node according to example embodiment N4 or N5, whereinthe radio network node comprises one or several of the following: anevolved NodeB (eNB), a Home Subscriber Server (HSS), a MobilityManagement Entity (MME).

Modifications and other variants of the described embodiments will cometo mind to one skilled in the art having benefit of the teachingspresented in the foregoing description and associated drawings.Therefore, it is to be understood that the embodiments are not limitedto the specific example embodiments disclosed and that modifications andother variants are intended to be included within the scope of thisdisclosure. Although specific terms may be employed herein, they areused in a generic and descriptive sense only and not for purposes oflimitation.

ABBREVIATIONS

-   -   3GPP 3^(rd) Generation Partnership Project    -   CC Credit Control    -   DL Downlink    -   DRX Discontinuous Reception    -   eNB eNodeB    -   eNodeB E-UTRAN NodeB    -   EPS Evolved Packet System    -   E-UTRA Evolved Universal Terrestrial Radio Access    -   E-UTRAN Evolved UTRAN    -   GPRS General Packet Radio Service    -   GTPv2-C The control plane part of the GPRS Tunneling Protocol        version 2.    -   HLR Home Location Register    -   HSPA High Speed Packet Access    -   HSS Home Subscriber Server    -   IE Information Element    -   IMSI International Mobile Subscriber Identity    -   IP Internet Protocol    -   IP-CAN IP Connectivity Access Network    -   LTE Long Term Evolution    -   M2M Machine-to-Machine    -   MAC Medium Access Control    -   MD Machine Device    -   MME Mobility Management Entity    -   MOD Modulo    -   MS Mobile Station    -   Msg Message    -   MTC Machine Type Communication    -   NAS Non-Access Stratum    -   PCEF Policy and Charging Enforcement Function    -   PCRF Policy and Charging Rules Function    -   PDN Packet Data Network    -   PDU Packet Data Unit    -   PGW PDN Gateway    -   RA Random Access    -   RRC Radio Resource Control    -   S1 The interface between the Radio Access Network and the Core        network in EPS.    -   S1AP S1 Application Protocol (a control plane protocol used        between an eNB and an MME)    -   SGSN Serving GPRS Support Node    -   SGW Serving Gateway    -   SI System Information    -   TS Technical Specification    -   UE User Equipment    -   UL Uplink    -   UMTS Universal Mobile Telecommunications System    -   USIM Universal Subscriber Identity Module    -   UTRAN Universal Terrestrial Radio Access Network    -   WCDMA Wideband Code Division Multiple Access

The invention claimed is:
 1. A method performed by a user equipment (UE)wherein the UE is configured to be either in an idle mode or in aconnected mode, the method comprising: applying a discontinuousreception (DRX) cycle during a time period when the UE is in transitionfrom the idle mode to the connected mode, and in which the UE performs aRandom Access procedure.
 2. The method according to claim 1, wherein theDRX cycle is a temporary DRX cycle.
 3. The method according to claim 2,wherein the temporary DRX cycle is applied only when the UE is intransition from the idle mode to the connected mode.
 4. The methodaccording to claim 2, comprising: ceasing to apply the temporary DRXcycle when the UE has transitioned to the connected mode.
 5. The methodaccording to claim 1, comprising: applying one or several DRXconfiguration parameters during the time period when the UE is intransition from the idle mode to the connected mode.
 6. The methodaccording to claim 1, comprising, prior to applying the DRX cycle duringthe time period when the UE is in transition from the idle mode to theconnected mode: transmitting a data message to a radio network node, thedata message comprising a request to apply the DRX cycle during the timeperiod when the UE is in transition from the idle mode to the connectedmode.
 7. The method according to claim 6, comprising, prior to applyingthe DRX cycle during the time period when the UE is in transition fromthe idle mode to the connected mode: receiving another data message fromthe radio network node, the another data message comprising anacknowledgement of said request.
 8. The method according to claim 1,comprising, prior to applying the DRX cycle during the time period whenthe UE is in transition from the idle mode to the connected mode:retrieving the DRX cycle to be applied during the time period when theUE is in transition from the idle mode to the connected mode.
 9. Themethod according to claim 8, wherein retrieving the DRX cycle to beapplied during the time period when the UE is in transition from theidle mode to the connected mode comprises: receiving a data message froma radio network node, the data message comprising information about theDRX cycle.
 10. The method according to claim 8, wherein retrieving theDRX cycle to be applied during the time period when the UE is intransition from the idle mode to the connected mode comprises:retrieving information about the DRX cycle from a memory associated withthe UE.
 11. The method according to claim 5, comprising, prior toapplying the DRX cycle during the time period when the UE is intransition from the idle mode to the connected mode: retrieving DRXconfiguration parameters to be applied during the time period when theUE is in transition from the idle mode to the connected mode.
 12. Themethod according to claim 11, wherein retrieving the DRX configurationparameters to be applied during the time period when the UE is intransition from the idle mode to the connected mode comprises: receivinga data message from a radio network node, the data message comprisingthe DRX configuration parameters.
 13. The method according to claim 11,wherein retrieving the DRX configuration parameters to be applied duringthe time period when the UE is in transition from the idle mode to theconnected mode comprises: retrieving the DRX configuration parametersfrom a memory associated with the UE.
 14. A method performed by a radionetwork node, the method comprising: transmitting a data message to auser equipment (UE) the data message comprising information about a DRXcycle to be applied by the UE during the time period when the UE is intransition from the idle mode to the connected mode, and in which the UEperforms a Random Access procedure.
 15. The method according to claim14, comprising: transmitting another data message to the UE, the anotherdata message comprising DRX configuration parameters to be applied bythe UE during the time period when the UE is in transition from the idlemode to the connected mode.
 16. The method according to claim 14,comprising: receiving another data message from the UE, the another datamessage comprising a request to apply a DRX cycle during the time periodwhen the UE is in transition from the idle mode to the connected mode.17. The method according to claim 16, comprising: transmitting anacknowledgment of said request to the UE.
 18. A user equipment (UE)configured to be either in an idle mode or in a connected mode, the UEcomprising: a processor; and a memory storing computer program code,which, when run in the processor causes the UE to apply a discontinuousreception (DRX) cycle during a time period when the UE is in transitionfrom the idle mode to the connected mode, and in which the UE performs aRandom Access procedure.
 19. The UE according to claim 18, wherein theDRX cycle is a temporary DRX cycle.
 20. The UE according to claim 19,wherein the memory stores computer program code, which, when run in theprocessor causes the UE to apply the temporary DRX cycle only when theUE is in transition from the idle mode to the connected mode.
 21. The UEaccording to claim 19, wherein the memory stores computer program code,which, when run in the processor causes the UE to cease to apply thetemporary DRX cycle when the UE has transitioned to the connected mode.22. The UE according to claim 18, wherein the memory stores computerprogram code, which, when run in the processor causes the UE to applyone or several DRX configuration parameters during the time period whenthe UE is in transition from the idle mode to the connected mode. 23.The UE according to claim 18, comprising a transmitter configured totransmit a data message to a radio network node, the data messagecomprising a request to apply the DRX cycle during the time period whenthe UE is in transition from the idle mode to the connected mode. 24.The UE according to claim 23, comprising a receiver configured toreceive another data message from the radio network node, the anotherdata message comprising an acknowledgement of said request.
 25. The UEaccording to claim 18, wherein the memory stores computer program code,which, when run in the processor causes the UE to retrieve the DRX cycleto be applied during the time period when the UE is in transition fromthe idle mode to the connected mode.
 26. The UE according to claim 25,comprising a receiver configured to receive a data message from a radionetwork node, the data message comprising information about the DRXcycle.
 27. The UE according to claim 25, wherein the memory storescomputer program code, which, when run in the processor causes the UE toretrieve information about the DRX cycle from a memory associated withthe UE.
 28. The UE according to claim 22, wherein the memory storescomputer program code, which, when run in the processor causes the UE toretrieve the DRX configuration parameters to be applied during the timeperiod when the UE is in transition from the idle mode to the connectedmode.
 29. The UE according to claim 28, wherein the receiver isconfigured to receive a data message from a radio network node, the datamessage comprising the DRX configuration parameters.
 30. The UEaccording to claim 28, wherein the memory stores computer program code,which, when run in the processor causes the UE to retrieve the DRXconfiguration parameters from a memory associated with the UE.
 31. Aradio network node, comprising: a transmitter configured to transmit adata message to a user equipment (UE) the data message comprisinginformation about a DRX cycle to be applied by the UE during the timeperiod when the UE is in transition from the idle mode to the connectedmode, and in which the UE performs a Random Access procedure.
 32. Theradio network node according to claim 31, wherein the transmitter isconfigured to transmit another data message to the UE, the data messagecomprising DRX configuration parameters to be applied by the UE duringthe time period when the UE is in transition from the idle mode to theconnected mode.
 33. The radio network node according to claim 31,comprising: a receiver configured to receive another data message fromthe UE the another data message comprising a request to apply a DRXcycle during the time period when the UE is in transition from the idlemode to the connected mode.
 34. The radio network node according toclaim 33, comprising a transmitter configured to transmit anacknowledgement of said request to the UE.
 35. The radio network nodeaccording to claim 31, wherein the radio network node comprises one orseveral of the following: an evolved NodeB (eNB), a Home SubscriberServer (HSS), a Mobility Management Entity (MME).